The present invention is generally directed to a device and method for reinforcement of the cardiac wall. The invention is particularly suited for the treatment of cardiac disease which result in atrial or ventricular dilation. The invention provides reinforcement of the cardiac wall during diastolic chamber filling to prevent or reduce cardiac dilation in patients known to have experienced such dilation or who have a predisposition for such dilation occurring in the future. The cardiac reinforcement structure is typically applied to the epicardial surface of the heart.
Cardiac dilation occurs with different forms of cardiac disease, including heart failure. In some cases, such as post-myocardial infarction, the dilation may be localized to only a portion of the heart. In other cases, such as hypertrophic cardiomyopathy, there is typically increased resistance to filling of the left ventricle with concomitant dilation of the left atria. In dilated cardiomyopathy, the dilation is typically of the left ventricle with resultant failure of the heart as a pump. In advanced cases, dilated cardiomyopathy involves the majority of the heart.
With each type of cardiac dilation, there are associated problems ranging from arrhythmias which arise due to the stretch of myocardial cells, to leakage of the cardiac valves due to enlargement of the valvular annulus. Devices to prevent or reduce dilation and thereby reduce the consequences of dilation have not been described. Patches made from low porosity materials, for example Dacron.TM., have been used to repair cardiac ruptures and septal defects, but the use of patches to support the cardiac wall where no penetrating lesion is present has not been described.
Drugs are sometimes employed to assist in treating problems associated with cardiac dilation. For example, digoxin increases the contractility of the cardiac muscle and thereby causes enhanced emptying of the dilated cardiac chambers. On the other hand, some drugs, for example, beta-blocking drugs, decrease the contractility of the heart and thus increase the likelihood of dilation. Other drugs including angiotensin-converting enzyme inhibitors such as enalopril help to reduce the tendency of the heart to dilate under the increased diastolic pressure experienced when the contractility of the heart muscle decreases. Many of these drugs, however, have side effects which make them undesirable for long-term use.
Accordingly, there is a need for a device that can reduce or prevent cardiac dilation and reduce the problems associated with such dilation.